{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/75235"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/75235","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"The Seismic Behavior of Steel Structures with Semi-Rigid Diaphragms","abstract":"This thesis investigates the torsional performance of steel structures with and without rigid diaphragm constraints through numerical simulations and evaluates the appropriateness of relevant design provisions in current seismic design codes. In the first part of the work, six theme structures with different (1) in-plane stiffness of diaphragm, and (2) horizontal configurations of vertical braced frames were designed and their performance evaluated through both nonlinear static and dynamic analyses. Comparisons of the analytical results between the structures with and without rigid diaphragm constraints indicate that the in-plane rigidity of the diaphragms affects the efficiency of in-plane force transfer mechanisms, resulting in different global ductility and strength demands. Rigid diaphragm structures exhibit higher global strengths as well as higher torsional rotation capacity because of the infinite in-plane stiffness of the diaphragm. Semi-rigid diaphragm structures have higher ductility demands due to the finite in-plane diaphragm stiffness. The inclusion of bi-axial forces in the analyses reduces the structural strength and increases the ductility demands on the peripheral frames. The axial forces in the collectors and chords that make up the diaphragm depend on (1) the sequence of brace buckling and (2) vertical configuration of the braced frames. The results show higher axial forces in collectors in the roof diaphragms, and higher chord axial forces in the third floor diaphragms. The shear connections in the beams that make up both the collectors and chords are susceptible to failure due to the significant increment of axial forces in those members. The conventional beam analogy used in design can severely underestimate the axial forces in chords and collectors when the structures step into the inelastic stage.","abstract_html":"This thesis investigates the torsional performance of steel structures with and without rigid diaphragm constraints through numerical simulations and evaluates the appropriateness of relevant design provisions in current seismic design codes. In the first part of the work, six theme structures with different (1) in-plane stiffness of diaphragm, and (2) horizontal configurations of vertical braced frames were designed and their performance evaluated through both nonlinear static and dynamic analyses. Comparisons of the analytical results between the structures with and without rigid diaphragm constraints indicate that the in-plane rigidity of the diaphragms affects the efficiency of in-plane force transfer mechanisms, resulting in different global ductility and strength demands. Rigid diaphragm structures exhibit higher global strengths as well as higher torsional rotation capacity because of the infinite in-plane stiffness of the diaphragm. Semi-rigid diaphragm structures have higher ductility demands due to the finite in-plane diaphragm stiffness. The inclusion of bi-axial forces in the analyses reduces the structural strength and increases the ductility demands on the peripheral frames. The axial forces in the collectors and chords that make up the diaphragm depend on (1) the sequence of brace buckling and (2) vertical configuration of the braced frames. The results show higher axial forces in collectors in the roof diaphragms, and higher chord axial forces in the third floor diaphragms. The shear connections in the beams that make up both the collectors and chords are susceptible to failure due to the significant increment of axial forces in those members. The conventional beam analogy used in design can severely underestimate the axial forces in chords and collectors when the structures step into the inelastic stage.","abstract_has_math":false,"creators":["Fang, Chia-hung"],"institution":"Virginia Tech","degree_name":"PhD","degree_level":"doctoral","degree_discipline":"Civil Engineering","degree_department":"Civil and Environmental Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Leon, Roberto T."],"committee_members":["Koutromanos, Ioannis","Easterling, William Samuel","Moen, Cristopher D.","Charney, Finley A."],"year":2015,"date_issued":"2015-09-10","date_published":"2015-09-10","updated_at":"2026-07-22T22:19:54Z","subjects":["Semi-rigid diaphragms","Rigid diaphragms","Pushover analysis","Nonlinear dynamic analysis"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:6270"],"render_values":[{"text":"vt_gsexam:6270","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/75235","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Leon, Roberto T."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Koutromanos, Ioannis","Easterling, William Samuel","Moen, Cristopher D.","Charney, Finley A."]},{"key":"dc:contributor.department","label":"Department","values":["Civil and Environmental Engineering"]},{"key":"dc:creator","label":"Author","values":["Fang, Chia-hung"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2017-03-04T07:00:16Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2017-03-04T07:00:16Z"]},{"key":"dc:date.issued","label":"Date","values":["2015-09-10"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Civil Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["PhD"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Semi-rigid diaphragms","Rigid diaphragms","Pushover analysis","Nonlinear dynamic analysis"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["vt_gsexam:6270"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/75235"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["This thesis investigates the torsional performance of steel structures with and without rigid diaphragm constraints through numerical simulations and evaluates the appropriateness of relevant design provisions in current seismic design codes. In the first part of the work, six theme structures with different (1) in-plane stiffness of diaphragm, and (2) horizontal configurations of vertical braced frames were designed and their performance evaluated through both nonlinear static and dynamic analyses. Comparisons of the analytical results between the structures with and without rigid diaphragm constraints indicate that the in-plane rigidity of the diaphragms affects the efficiency of in-plane force transfer mechanisms, resulting in different global ductility and strength demands. Rigid diaphragm structures exhibit higher global strengths as well as higher torsional rotation capacity because of the infinite in-plane stiffness of the diaphragm. Semi-rigid diaphragm structures have higher ductility demands due to the finite in-plane diaphragm stiffness. The inclusion of bi-axial forces in the analyses reduces the structural strength and increases the ductility demands on the peripheral frames. The axial forces in the collectors and chords that make up the diaphragm depend on (1) the sequence of brace buckling and (2) vertical configuration of the braced frames. The results show higher axial forces in collectors in the roof diaphragms, and higher chord axial forces in the third floor diaphragms. The shear connections in the beams that make up both the collectors and chords are susceptible to failure due to the significant increment of axial forces in those members. The conventional beam analogy used in design can severely underestimate the axial forces in chords and collectors when the structures step into the inelastic stage."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph. D."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["ETD"]},{"key":"dc:title","label":"Title","values":["The Seismic Behavior of Steel Structures with Semi-Rigid Diaphragms"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Leon, Roberto T."],"dc:contributor.committeemember":["Koutromanos, Ioannis","Easterling, William Samuel","Moen, Cristopher D.","Charney, Finley A."],"dc:contributor.department":["Civil and Environmental Engineering"],"dc:creator":["Fang, Chia-hung"],"dc:date.accessioned":["2017-03-04T07:00:16Z"],"dc:date.available":["2017-03-04T07:00:16Z"],"dc:date.issued":["2015-09-10"],"dc:description.abstract":["This thesis investigates the torsional performance of steel structures with and without rigid diaphragm constraints through numerical simulations and evaluates the appropriateness of relevant design provisions in current seismic design codes. In the first part of the work, six theme structures with different (1) in-plane stiffness of diaphragm, and (2) horizontal configurations of vertical braced frames were designed and their performance evaluated through both nonlinear static and dynamic analyses. Comparisons of the analytical results between the structures with and without rigid diaphragm constraints indicate that the in-plane rigidity of the diaphragms affects the efficiency of in-plane force transfer mechanisms, resulting in different global ductility and strength demands. Rigid diaphragm structures exhibit higher global strengths as well as higher torsional rotation capacity because of the infinite in-plane stiffness of the diaphragm. Semi-rigid diaphragm structures have higher ductility demands due to the finite in-plane diaphragm stiffness. The inclusion of bi-axial forces in the analyses reduces the structural strength and increases the ductility demands on the peripheral frames. The axial forces in the collectors and chords that make up the diaphragm depend on (1) the sequence of brace buckling and (2) vertical configuration of the braced frames. The results show higher axial forces in collectors in the roof diaphragms, and higher chord axial forces in the third floor diaphragms. The shear connections in the beams that make up both the collectors and chords are susceptible to failure due to the significant increment of axial forces in those members. The conventional beam analogy used in design can severely underestimate the axial forces in chords and collectors when the structures step into the inelastic stage."],"dc:description.degree":["Ph. D."],"dc:format.medium":["ETD"],"dc:identifier.other":["vt_gsexam:6270"],"dc:identifier.uri":["http://hdl.handle.net/10919/75235"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Semi-rigid diaphragms","Rigid diaphragms","Pushover analysis","Nonlinear dynamic analysis"],"dc:title":["The Seismic Behavior of Steel Structures with Semi-Rigid Diaphragms"],"dc:type":["Dissertation"],"thesis:degree_discipline":["Civil Engineering"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["PhD"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:54Z"}